One of signal transmission interfaces between two circuits is a signal transmission interface called PCI Express® (hereinafter, PCIe). PCIe has gone through several generations of evolution, and, with each succeeding generation, the transmission speed increases. A finer process is needed to increase the transmission speed, which makes a soft error more likely to occur.
PCIe is originally a signal transmission interface that performs serial data transmission, but PCIe can also transmit parallel data, which is a bundle of a plurality of pieces of serial data, by synchronizing the parallel data. In fourth-generation PCIe Gen4, transmission of parallel data is made possible by providing a frequency division circuit for each serial data of PCIe and synchronizing the frequency division circuits.